A detailed plan of investigation is presented which enables us to evaluate those factors which are responsible for the large rate enhancements which we previously observed in the hydrolysis of o- carboxybenzal chloride. Secondary deuterium isotope effects in conjunction with structure-reactivity correlations for selected benzal chlorides forms the basis for this evaluation. Certain model acetal reactions will also be investigated in order to evaluate the possibility that the mechanism of action of lysozyme involves rate-determining attack of Asp-52 on the performed carbonium ion.